Knee actuating mechanism for milling machines



-- 18 1946. m E T 2,402,290

7' KNEE ACTUATING MECHANISM FOR MILLING MACHINES 3 Sheets-Sheet 1 Filed Sept. 9, 194:

- 22 1 27 '77 a a H 16 June 18, 1946. L. F. NENNINGER ETAL I KNEE ACTUA'IING MECHANISM FOR MILLING MACHINES Filed: Sept. 9, 1943 3.- Sheets-Sheet 2 Iz'cz? INVENTOR."

June 18, 1946. L. F. NENNINGER ETAL KNEE ACTUATING MECHANISM FOR MILLING MACHINES Filed Sept. 9, 1943 3 Sheets-Sheet 5 INVENTOR. liJrfpf/l /r/m m p .oxwj /va/v v ATTO EY.

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remi sions is, 1946 r UNITE-D sT grEs KNEE ACTUATING MECHANISM FOR I IILL- INGMA Lester-F. Nenninger accrua s. cincinnathohimelfllnorstoTheflincinnatimll- Cincinnati,

in: Machine 00., tion of Ohio Ohio, a corpora-.

Application September 9, 1943, Serial No. 501,714

1 'iClaims.

This invention relates to machine tools and more particularly to improvements in milling ma- One of the objects of this invention is to make improvements in the operating and control mechanism of a milling machine.

Another object of this invention is to reduce the power required to operate the knee elevating mechanism, thereby facilitating manual operation.

A more particular object of this invention'is to provide an improved anti-friction knee elevating mechanism for a milling machine or the like.

A iurther object of this invention is to conmm a knee elevating mechanism in such a manher that the coolant normally utilized with such a machine may be led or conducted in a heat exchanging relationship with the operating parts and thereby uniformize the temperature throughout the knee mechanism and thus preserve any precision setting of the machine.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification, considered in i 25 amount of friction is developed in the screw and coniunction with the accompanying drawings forming a part thereoi'and it is to be understood that any modifications may .be made in the exact structural details there shown and described,

within the scope of the appended claims, without departing from or exceeding the spirit of the invention. I v

Referring to the drawings in which like reference numerals indicate like or similar parts:

Figure 1 i an elevation of a machine tool embodying the principles of this invention.

I'lgumiiisasectiononthelineI-loflisure 1. g

Iigure 3 is a section on the line 3-3 of Figure 1.

Figure 4 is a detail section on the line 4-4 of Figure 3.

Figure 5 is a detailed view in elevation of the exterior of the nut member as viewed on the line Figure 8 is a detail section on the line H mines I is a section on the line i--I of Figare This invention relates to elevating mechanisms for vertically moving machine parts and will be described in connection with a movable part of amachinetoolsuchasthekneeofamillingmachine. In Figure 1 of the drawings there is shown a typical milling machine having a column, which is indicated by the reference numeral II,

2 on which is formed guideways ii for receiving a knee I! for vertical movement or adjustment. This movement or adjustment is primarily for the purpose of changing the relationship between the top surface of the table it. which is supported on the knee through the medium of an interposed saddle #4, relative to the axi of a cutter spindle II, which is Journa'ied for rotation in the oolumnili. 10 The table i3 is supported on the saddle it for translation in a horizontal plane, while the die i4 is supported for translation on the knee in a horizontal plane but in a direction at right angles to the direction of movement of the table. It will be obvious that any change in the position of the knee, which might be caused oyuneven e'i sions thereof, may afiect the accuracy of any machining operation.

It is common practice to raise or lower the knee through the medium of a screw and nut mechanism, but it will be noted that the com bined knee, saddle and table hang from the column in cantilever fashion, and since the total weight of these parts is very considerable a great nut mechanism, which, in addition to the added weight which has to be moved, requires a large amount of power toeflect any change in position. an Even although reduction gearing is utilized it is ally eii'ect adjustment of this structure.

By means of this invention the amount oi friction developed in an elevating movement is very greatly reduced, thereby facilitating manual operation as well as reducing the power required during a power operation.

' Referring more particularly to Figures 1 and 2, the machine is provided with a base it upon which is formed an upstanding pedestal ii. The

upper end of this pedestal has a counter-bore it in which is secured a nut member IS. The interior bore of the nut member has a spiral thread 2| turned therein, the thread being of semi-cira cular cross section. The elevating screw it section of the thread also being of a semi-circular cross section. The screw it is keyed at 23 to a bevel gear 24 which is supp rted for restill a strenuous job for the operator to manuhas a spiral thread '22 formed thereon, the cross tuated by either manual or power means to be described.

Two ets of recirculating balls, indicated generally by the reference numerals 21 and 28, are interposed between the threads on the screw and the threads of the stationary nut member. It is, of course, necessary to prevent the balls from escaping and therefore return connections are provided for each set and the construction of these return connections is shown more particularly in Figures and 6. From these figures it will be noted that the nut member is provided with a flat face 29 and return tubes 20, which are somewhat U-shaped, have their legs 3| and 22 inserted through bores 33 and 34 in such a manner a to collect the balls from an upper convolution of the thread and return them to a lower convolution, or vice-versa, and in such a manner as to prevent escape of the balls. The return tubes 30 are held in position by a clamping plate 35 which is fastened to the face 29 as by screws 36. The plate has two diagonal grooves 31 formed therein which receive the tubes and hold them tightly in position.

By means of the plurality of sets of recirculating balls, friction between the screw and nut is very greatly reduced. In fact, the friction is reduced to such a point that there is a tendency due to the weight of the parts during downward movement thereof to overrun, and therefore a braking means has been provided in order to retard acceleration of the parts during downward movement. In order to more clearly understand the operation of the braking mechanism, the transmission for driving the bevel gear 24 will be described first.

A typical form of mechanism is hown in Figure 3 and comprises a power driven shaft 3! which may be driven from a prime mover in the column in any suitable manner. This shaft carriesa rapid traver ear 3! which is supported for free rotation in arings 40 in a wall 4i of the knee. and the gear may be operatively connected to the shaft through the medium of a clutch 42. The shaft 38 also carries a feed gear 43 which is operatively connected through suitable means, not shown, to a bevel gear 44. Any suitable form of variable feed transmission may be interposed between the gears 43 and 44, but since the same forms no part of the present invention it has not been illustrated. Suffice it to .say that the gear 44 is a feed gear, the gear 39 is a rapid traverse Bear and the clutch 42 determines which gear shall be effective.

The bevel gear 44 drives through a bevel gear 45 an overrunning clutch, indicated generally by the reference numeral 48, whereby when the rapid traverse clutch 42 is disengaged the output shaft 41 of the overrunning clutch is rotated at a slow speed. This shaft carries a main drive gear 48. when the rapid traverse clutch 42 is engaged, the gear 38 drives the gear 48 through the intermediate idler gear couplet 49" and the overrunnlng clutch slips'to permit the faster drive.

The main drive gear 48 inter-meshes directly with a gear 5| supported for free rotation on shaft 52 and the idler gear 48 is so positioned that it intermeshes with a gear 53 whereby the gears El and 53 rotate in opposite directions. An intermediate clutch member 54 keyed to the shaft 52 may be alternately shifted into mesh with either the clutch gear Si or the clutch gear 83 for rotation of the saddle cross screw 5!. In addition, the gears ii and i3 intermesh with a second pair of gears 58 and 51 which are likewise rotated in opposite directions, and an intermediate clutch member 58 may be alternately shifted to connect these gears for rotation of shaft 58.

This shaft carries a bevel gear 80 which intermeshes with the bevel gear 24 shown in Figure 2 whereby the elevating screw may be power rotated in either a clockwise or counterclockwise direction. The gear 51 has another gear 81 integral therewith which intermeshes with a gear 62 supported on the end of a shaft 63. This shaft is journaled at 64 in a fixed wall 65 of the knee, and the other end of the shaft is Journaled at it in the front wall 61 of the knee. The shaft 43 is utilized to impart manual rotation to the elevating screw, and to that end is provided with a manually operable handle 88 which is slidably mounted on the outer end of the shaft. The hub 69 of the handle is connected by interengaging clutch teeth 10 to a clutch member II which is pinned at 12 to the shaft 63.

A spring 13 is interposed between the members 69 and H for normally maintaining the member 69 out of operative engagement with the clutch member H, whereby during power rotation the handle 88 will not be revolved. It has been found, that on account of the great reduction in friction effected by the improved nut mechanism, that there is a tendency to overrun during downward movement of the knee, and therefore, means have been introduced to effect a braking action during such downward movement so that the moving member will not gain too much momentum. To this end, the shaft 63 has mounted thereon for free rotation a sleeve 15. This sleeve carries a plurality of plates 18 splined thereon as shown in Figure 7 between which are interposed a second plurality of plates 11 which, as shown in Figure 7, are provided with ears ll which project into slots I8 formed in a fixed sleeve 19a and thereby are held against rotation. These plates constitute a braking means and the amount of friction developed is determined by the adjustment of a spring by which the plates are squeezed between member 8i and the adjusting nut 82.

Referring to Figure 4, the member 81 is so formed as to provide a ratchet means whereby upon rotation of the shaft 63 the brake becomes effective, but upon rotation in the other direction the brake becomes ineffective. The purpose of this is to have the brake effective during down-; ward movement of the knee structure, but in--' effective during upward movement thereof. This: ratchet mechanism comprises a, series of rollers 83 which are normally urged outward by springs l4 in a direction to wedge between the interior bore 85 of a member 86 which is pinned to the shaft 83 at 81. The shaft 83 thus drives through the pin 81, the member 86, which upon rotation in a clockwise direction, as viewed in Figure 4, will cause the rollers 83 to move in a wedging direction, causing rotation of the member 8| which is splined to the sleeve 15 through the splines I.

Upon rotation in the opposite direction the rollers 82 are urged in a non-wedging direction whereby slippage takes place and the member it is not actuated. It will now be apparent that regardless of whether the shaft 82 is rotated manually by the handle 48 or is rotated by the power mechanism through gear 6|, the braking mechanism will function during one direction of rotation of the shaft and will be ineffective during the other and in an automatic manner,

Referring to Figure 2 the pedestal H has an interior bore through which the elevating screw passes and the lower end or this bore is closed by a cup-shaped member 89. This entire bore may be filled with lubricating oil for lubricating the screw and nut mechanism. In order to maintain a more uniform temperature throughout the pedestal and in relation to the knee, passages have been formed in the pedestal and in the knee in such a manner that coolant applied to work on the table may be conducted to a reservoir 90 formed in the base 16 in'such a manner that it will pass in heat-exchanging relationship to the pedestal.

In this connection the knee is provided with a passageway 9| which normally receives coolant from the table and this passage is connected to an opening 92 in the inner wall of the knee which surrounds the pedestal. By providing this open-. ing, the coolant may flow through an annular passage 93, the inner wall of which comprises telescoping tubes 94 and 95, the tube 94 being fixed with the base member I6 and the tube 95 being attached to the knee.

The outer wall of this annular passage is composed also of a series of telescoping tubes 96, the inner one of which is attached by screws 91 to the knee for movement therewith and the outer tube 98 is attached by screws 99 to the base It. The coolant thus flows in close relationship to the telescoping tubes 94 and 95 and thereby serve to conduct heat away from the pedestal I! to maintain the temperature thereof substantially uniform and thereby prevent expansion thereof which might tend to vary the height of the nut member in the upper extremity thereof and cause a variation in the height of the table relative to the base of the machine. The coolant flowing through the passage 93 may flow through a interconnecting passage I00 which is formed in the base it to the reservoir 90.

Suitable mechanism which forms no part of the present invention is, of course, utilized for withdrawing the coolant from the reservoir 90 and pumping it to a suitable elevation for application to work on the table.

There has thus been provided an improved mechanism for elevating a movable member of a machine tool, such as a milling machinein a manner which greatly reduces the friction and concomitantly the power required to elevate the knee. Due to the great reduction in friction effected, automatic braking means have also been provided which prevent undue acceleration of the parts during downward movement. The mechanism has also been so contrived that utilization may be made of the coolant supply normally available in such machines for maintaining a more uniform temperature of the operating parts and thereby preserving the accuracy and precision of the machine.

What is claimed is:

1. In a machine toolhaving a tool support and a work support, the combination of means for effecting relative vertical adjustment between said supports including an anti-friction connection between the final driven member of said adlusting means which is carried by one of said supports and its cooperative member carried by the other support, means to effect reverse actuation of said adjusting means to raise or lower the movable support, and means automatically responsive to the direction of actuation that causes 6 means being automatically released upon reversal in the direction of actuation.

2. In a knee elevating mechanism. for a milling machine, the combination with a knee mounted on a fixed sup rt, of an elevating screw carried by the knee, a cooperating anti-friction nut member carried by the fixed support, means to effect relative rotation between the screw and nut in opposite directions to raise or lower the knee, a braking means, and means responsive to the direction of said rotation for automatically applying said braking means to said rotating means during lowering of the knee, and releasing said braking means upon elevation of the knee.

3. In a milling machine having a column, a tool spindle journaled in the column and a knee vertically adjustable on the column for positioning work relative to the spindle, the combination of actuating means for vertically adjusting the knee including an elevating screw, an anti-friction nut member for supporting the screw, means to effect relative rotation between the screw and nut, a braking means applicable to said rotating means to produce a retarding effect thereon during downward movement of the knee and non-'ap-' plicable during upward movement of the knee,

- and means to adjust said braking means to vary on the final driven member, said last-named the retarding effect thereof.

4. In a milling machine having a column, and a knee adjustably mounted on the column, the combination of mechanism for raising and lowering the knee including an anti-friction screw and nut mechanism, a manually operable shaft carried by the knee, means operatively connecting the shaft for effecting relative actuation between the screw and nut, a frictional braking means, and a unidirectional clutch interconnecting said shaft with said braking means whereby upon rotation of said shaft in one direction for raising the knee the braking means will be ineffective and upon rotation in the other direction the braking means will become effective.

5. In a milling machine, the combination with a column and a knee adjustably mounted on the column for vertical movement relative to a tool spindle carried by the column, the combination of means for effecting said movement including an elevating screw carried by the knee, an antifriction nut member fixedly supported in coop-' erative relation to said screw, means carried by the knee for rotating said screw including a shaft, a. friction-creating device including a plurality of fixed plates, a plurality of movable plates, means to adjust the friction between said plates, and a unidirectional clutch operatively connecting said movable plates to said shaft whereby said friction device will be effective during lowering oi said knee.

6. In a milling machine having a column, a knee adjustably mounted on the column, a tool spindle carried by the column, the combination of means for raising and lowering said knee includ ing a power shaft journaled in the knee, an antifriction screw and nut member for effecting movement of the knee, said screw being journaled in the knee, means for operatively connecting said screw to the power shaft, a friction-creating device, and means responsive to one direction of rotation of said power shaft for automatically connecting said friction device thereby to produce a retarding effect during downward movement of the knee.

7. In a milling machine having a column, a tool spindle journaled in the column and a knee slidably mounted on the column for movement toward and from the spindle. thecombination of means for eilectinz nid movement including 5 power operable shgft and a manually operable shaft journaled in knee, en anti-friction screw and nut one or which 1; fixed and the other immaled in the knee, mean; onentively connectinzmid chute to said movable member, a iriction ci'eatinl device, and means responsive to rotation of either of aid mm in a.

direction to move the knee iron: the lntndie to render said friction device eitective in retnrdinl movement of the knee, said friction creating device being releasable upon reveral in the direction of said rotation. e 

